Custom Grid ColumnHeader

I'm trying to port my custom Grid from 2.0 to 3.0.
In my grid I have a custom ColumnHeader with my own DOM structure.

In 2.0 this was easy to do, just override the onRender method. But in 3.0 the DOM structure is created directly in the constructor. Since the ColumnHeader don't have a "default" constructor I need to call the super(container, cm) in my custom constructor witch creates the DOM elements that I want to override.

I would need the ColumnHeader to ether implemented the ApperencePattern or move the DOM creation to a method that can be overridden. I that something that is planed?